The more than 600 neurological diseases caused by genetic disorders, injuries/infections and aging-related degeneration uniquely challenge the quality of life as they typically impair cognitive, sensory and motor functions. Although there is an exponential increase in the prevalence of such diseases, partly due to the aging population, few effective treatments are available. Though new technologies have enabled the rapid development of new therapeutics, these often fail in clinical trials, largely due to inefficiency in translating/validating animal-based results in humans. Thus, there is a growing need for a humanized in vitro (outside the body) model for healthy and diseased nerves in order to further the fundamental understanding of neuroscience and develop potential interventions for neuro-abnormalities. This project addresses this need by developing and validating a personalized nerve tissue model composed of neurons and supporting cells derived from neural stem cells and designed to structurally and functionally mimic native nerves. This outcome has potential for broad society impact, including: 1) providing a scientific basis to realize personalized regenerative medicine amid fast rising demand for long-term efficacy in the current ageing society; 2) providing a personalized drug test bed which could lead to the development of patient-tailored therapeutics; 3) leading to development of novel implants that enable currently unachievable regeneration of damaged spinal nerves and 4) providing ideal platforms for many fundamental neuroscience studies. Students associated with the project will be trained at the interface of materials science, nanotechnology, neuroimaging and neuroscience. The education and outreach initiatives center on under-represented groups in STEM, including: 1) an undergraduate research partnership between the University of California-Riverside (a Hispanic serving institution)) and California Baptist University (a primarily undergraduate institution), 2) various K-12 outreach programs, and 3) integration of research outcomes into both undergraduate and graduate courses.
The objective of this project is to develop a tissue morphogenesis strategy to produce a tissue structurally and functionally comparable to native nerve tissues and to validate the structure/functionality by non-destructive imaging for longitudinal observations. The work builds on the lab's recently developed technology to enhance neural cell activities; simultaneous mechanical and electrical (mechano-electrical) stimulation a) facilitated neurite elongation and b) activated glial cells to express neourotropic factors. The research plan is organized under two tasks. Task 1 is to develop a strategy to engineer spinal nerves structurally and functionally comparable to the native tissues via mechano-electrical stimulation by using electrospun piezoelectric PVDF-TrFE scaffolds that can be vibrated acoustically. The initial step is to determine the optimal mechano-electrical stimulation regimen for the functional enhancement of cellular constituents of the nerve (neurons, oligodendrocytes and astrocytes) derived from human neural stem cells (NSCs) by adjusting the thickness of piezoelectric scaffolds seeded with the cellular constituents (each cell type separately seeded). The next step is to determine the effects of mechano-electrical stimulation on the multi-phenotype differentiation of human NSCs by seeding H9-derived NSCs on the scaffolds that will then undergo daily stimulations for 2 hrs/day for 6 days before being assessed by counting the number of cells of each differentiated type. After optimization of the differentiation process, nerve generation from bottom-up (neurons, oligodendrocytes and astrocytes allowed to self-assemble the nerve structure) and top-down (simultaneously induce the differentiation of NSCs towards the three cell phenotypes and structural assembly) approaches will be compared after an appropriate stimulation duration, i.e., after myelination and tissue morphogenesis has occurred. The cell/scaffold constructs will then be rolled to form a cylindrical shape and subjected to standard nerve conduction testing and histological examination. Task 2 is to validate the morphological and functional characteristics of the engineered nerve tissue via non-destructive polarization-sensitive optical coherence tomography (PS-OCT). PS-OCT based biomarkers for nerve viability in the central nervous system will be identified by comparing excised spinal cords from a mouse model of multiple sclerosis (MS) with spinal cords from age matched controls. PS-OCT, which is capable of imaging within and through the scaffolding material, will then be used to quantitatively monitor the morphogenesis and structure of the engineered nerve structures, which will enable optimization of the desired end points for cell density and degree of myelination through comparison to optical biomarkers obtained from the control spinal cord samples. Finally, PS-OCT will be used to quantify the loss of structure and functionality resulting from chemically induced (lysolecithin) degeneration in engineered nerve structures. Changes in optical measures during degeneration are expected to lead to parameters that can be optimized to model the degeneration observed in the pathologic/MS spinal cord samples.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
